Environmental concerns and governmental regulations require that motor vehicles have fuel management systems that control fuel tank ventilation to reduce emissions of fuel vapors into the atmosphere and that close when the vehicle is inclined or rolls over to prevent a hazardous liquid fuel leak.
Fuel vapor can be created in the fuel tank by temperature differences between the fuel tank and a liquid fuel from a fuel pump, as well as by sloshing and agitation of the fuel in the fuel tank during normal vehicle operation. The pressure buildup resulting from the creation of fuel vapors must be relieved properly.
Fuel vapor recovery systems are commonly employed to remove excess fuel vapor from the fuel tank. Such systems may include a canister with activated charcoal, which receives fuel vapors through a valve assembly mounted in the top of the fuel tank and which communicates with an intake manifold of the vehicle engine for withdrawing fuel vapor from the fuel vapor recovery canister during operation of the engine.
One conventional valve assembly uses a portion of a float to close or plug its vent opening on an incline or during a rollover to prevent liquid fuel from discharging through the valve assembly into the vapor recovery canister. Responsiveness of the float in closing the vent opening is largely a function of float size, which is often limited by its surrounding valve housing. If the float is sluggish to respond or has an insufficient closing force on the incline or during the rollover, the liquid fuel can discharge through the vent opening.
To reopen the vent opening after the vehicle has been inclined or after the rollover, the typical valve assembly may use a “peel-away” device connected to its float. The peel-away device is intended to avoid reopening problems known in the valve industry. However, the peel-away device may not seal very well due to its flimsy construction.
There is a need in the automotive valve industry for a vent valve that addresses environmental concerns, complies with governmental regulations and exhibits a simple construction so as to be cost-effective and have a long service life.